Shulou(Shulou.com)06/02 Report--

This article mainly explains "what is the working principle of RS485". Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn how RS485 works.

What is RS485?

● RS485, also known as TIA-485 (- A) or EIA-485, is a method of serial communication between computers and devices similar to RS232.

● RS485 is not only a single device-to-device interface, but also a communication bus for forming a simple network of multiple devices.

● RS485 allows up to 32 devices to add half-distance half-duplex communication to a single pair of wires, while the maximum distance of a ground wire is 1200 meters. (if you want to extend the length and number of nodes of your network, you can easily do this using repeaters. )

Because RS485 has a wide common mode range, it can transmit data over long cables in noisy environments, so RS485 is commonly used as a protocol for POS, industry, telecommunications, especially in noisy environments. RS485 is also common in computers, PLC, serial servers, microcontrollers and intelligent sensors in science and technology applications.

How does RS485 work? (wiring arrangement)

● in RS485, data is transmitted in a differential manner through two stranded wires (commonly referred to as "twisted pair cables"). Because of the distortion, RS485 has high anti-noise ability and long-distance transmission ability.

● as shown in the figure above, the noise current generated by the ambient magnetic field is in the opposite direction to the current in other parts of the cable, thus making the noise current lower than that of an ordinary straight cable.

In RS485 networks, ● can be configured in two common ways: 2-wire (half-duplex system) or 4-wire configuration (full-duplex system)

2-wire half-duplex system

● can only transmit data in one direction at a time in a RS485 2-wire half-duplex system. (you can only send or receive data at a time) in this setting, host TX and RX signals share a pair of wires, which means you can save installation costs and nodes can communicate with each other.

● in this setting, the transmitter and receiver are connected to each node on a pair of twisted pair. However, in this setting, it is limited to half-duplex and requires attention to turnover delays.

4-wire full-duplex system

● uses this RS485 4-wire full-duplex system, where data can be passed back and forth between nodes at the same time. (you can receive and send data at the same time.) in this system, two wires will be used for transmission and the other two wires will be used for reception.

● in this setting, a main port with a transmitter is connected to each node that receives data on a pair of twisted pair. However, in this full-duplex setting, they are limited to master-slave communication where nodes cannot communicate with each other.

At this point, I believe you have a deeper understanding of "how RS485 works". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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